Doing the new Scarlet Halls on a leveling alt is a pain in the ass. Everyone levels expecting to bulldoze the place on cruise control. Now you can have full wipes by not knowing the mechanics/warnings ahead of time.
Reminds me of doing lowbie SFK in Cata. Godfrey's bullets hurt a lot more than any other ability, and people didn't tend to have interrupts and decurses at level 18.